[ARC5] 28 volt high-current supplies?

[Charles]

It's not the capacitor on phase A.  Oh pooh. Now I have to look for 
zebras rather than horses...

Yes, I am aware of the basic motor physics ;) That "about a second" is 
with a stiff supply. Mine is apparently not stiff enough <that's what 
she said> :D

My original plan was to acquire a 618T with the 400 Hz three-phase 
supply - usually much cheaper than the 28 vdc or the 400 Hz single phase 
versions. But this inverter is becoming a real white elephant. It would 
be running all the time, not PTT like the ART-13.

Anyway I am tempted to go buy a pair of car batteries and find out, just 
because I'm stubborn that way! (My two "ARC-5" receivers have their 
dynamotors, but I only run one at a time, and the 28v supply I built 
with a handy Stancor RT-204 transformer has no trouble).

Charles, WB3JOK/0 since '76


On 2/26/22 15:13, Christopher Bowne wrote:
> No, just a an Ames (Harbor Freight) 80 buck multimeter with a clamp on 
> AC or DC ammeter.
>
> Peak current is always at initial 0 RPM, as the motor winds up the 
> counter EMF brings the current down in about a second. Basic
> DC motor physics.  Considering the instrument pedigree I take no 
> responsibility for the accuracy of the reported result.
>
> As an alternative to floating batteries on the output of a DC supply, 
> one could implement a step starter circuit, but you would need
> some hefty dropping resistors and contactor relays.  Wouldn’t lend 
> itself to quick PTT operation on voice.
>
> Chris AJ1G
> Stonington CT
>
> Sent from my iPhone
>
>> On Feb 26, 2022, at 15:38, Charles <charlesmorris800 at centurytel.net> 
>> wrote:
>>
>> Thanks, there's a data point of 5 times the nameplate.. What was the 
>> decay time of that 160 amp peak (did you use a scope)?
>>
>> If I HAD a couple of spare car batteries I'd certainly try them ;) 
>> but have you seen the prices lately? they start at $55 plus core plus 
>> tax at Wally World...
>>
>>
>> On 2/26/22 13:37, Christopher Bowne wrote:
>>> I’ve measured the peak inrush current on my ART-13’s DY-17A 
>>> dynamotor,  it was a nominal 160 amps.  Just float a couple of 12 
>>> batteries across the output of your supply, make sure that they are 
>>> fully charged and full sized automotive or deep cycle marine type, 
>>> small one may not deliver enough peak current to preclude tripping 
>>> the output breaker in on your high current supply.
>>>
>>> Chris AJ1G
>>> Stonington CT
>>>
>>> Sent from my iPhone
>>>
>>>> On Feb 26, 2022, at 13:57, Charles via ARC5 <arc5 at mailman.qth.net> 
>>>> wrote:
>>>>
>>>> I am sure I would have no trouble starting a DY-17 with a 33 amp 
>>>> full load rating. This beast is 3.5 times that full load draw and 
>>>> consequently any surge current would likely also be 3.5 times that...
>>>>
>>>> Anyway I am going to investigate shorts on the AC side, and my 
>>>> prime suspect is the (noise reduction?) capacitor on A phase. Hope 
>>>> it's not the armature. It does have a repair request tag from the 
>>>> 80's or 90's (don't remember at moment) and an unreadable 
>>>> "Serviceable" tag. The electromechanical regulator (carbon piles!) 
>>>> will get a look after I check the cap. Something else I have no 
>>>> experience with.
>>>>
>>>>
>>>>
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